Bone telephone receiver



Dec. 2, 1941. w. T. WEIDENMAN. sR

BONE TELEPHONE RECEIVER Filed March 1'7, 1938 lNvENToR O7 BY f f. 4 RNEY Patented Dec. 2,' 1941 BoNE TELEPHONE RECEIVER William T.y Weidenman,

Sr., Spring Valley.

N. Y., assignor to Telephonics Corporation, New York, N. Y., a corporation of New York Application March 17, 1938, Serial o. 196,329

4 Claims.

This invention relates to bone telephone receivers and has particular reference to a bone telephone receiver that operates on the reaction principle.

Bone telephone receivers are particularly adaptable for communication during gun dre, in aeroplanes, or in other places where the level of surrounding sound is of such magnitude as to make extremely dliiicult the clear perception of sound by the usual air conduction method. Under such conditions the pitch of the receiver has a material bearing on the sound perception, since transmitted sounds at normal pitch and frequency are frequently difficult to distinguish even with bone conduction, because of the normal response of the hearing organs to the surrounding predominating sound. Different levels of predominating sounds require a different pitch of the bone receiver to enable clear perception above the predominating sounds.

In accordance with the present invention, a bone telephone receiver is provided *for use by those of normal hearing, as well as by those of subnormal hearing, which is adjustable as to pitch, and also-as to corresponding magnetic air gap, so that the most sound-perceptive combination is obtainable under the specific conditions of use, whether it be due to adeafened condition or a condition where predominating surrounding sounds render diilicult normal hearing at those sound levels.

The present invention comprises a bone receiver of the reaction type in which three preferred adjustments are provided, namely, first, a positive adjustment of the magnetic air gap without requiring bodily shifting of parts or adjustment of one element of a vibratory part comprising several cooperating elements; second, an adjustment of the center of mass of a vibratory part of the receiver for altering the frequency thereof, which in some cases is made most eil'ective by simultaneous air gap adjustment; and third, an arrangement for varying the length of the stroke oi a vibratory part of the receiver to change the pitch thereof, which also is made most effective in some cases by simultaneous air gap adjustment. All of these adjustments may be made in the reaction type bone telephone receiver of this invention in a simple way without requiring dismounting of any part, whereby the receiver may be readilyand rapidly adapted to use under the abnormal conditions mentioned.

For a more complete understanding of the invention, reference may be had to the accompanying drawing, in which:

Figure 1 is a longitudinal section through the bone telephone receiver of this invention as seen y along the line l-I of Fig. 2; Fig. 2 is a vertical section therethrough as seen along the line 2-2 of Fig. 1;

Fig. 3 is a plan view of the receiver with the housing removed;

Fig. 4 is a vertical section as seen along the line 4-4 of Fig. 1: Y

Fig. 5 is a bottom view of the device with the cover plate partially broken away to illustrate a detail of the pitch adjusting means; and

Fig. 6 is an end view of the receiver with thehousing removed.

Referring to the drawing, numeral I0 designates a base, preferably formed of a synthetic resin or the like, and having anchored in the upper surface thereof a stud II inserted through an opening in one end of the L-shaped plate I2 and riveted over as shown in Figs. l and 4, so that plate I2 is supported et one end and extends in parallel spaced relation to the upper surface of shaped, resilient, deflectable spacer I1 and supporting thereon one end of a bar magnet I9, whose other or free end is closely spaced with respect to the end of the pole piece I3` to form the magnetic air gap 20.. I'he plate I2, pole pice I3, and spacer il are formed of magnetically permeable material to a'iord with the magnet I9 closed flux path across the gap 20.

The air gap 2li may be increased at will by tightening bolt I6 to deflect by compression the resilient, channel-shaped spacer Il sufficiently to provide the desired width of the air gap 20. By relieving or loosening bolt I6, the spacer will expand, thus reducing the width of the air gap 20.

It will be observed that this air gap adjustment is positive, remaining unchanged after being once set, the change being effected without dismounting or bodily shifting any `part, and'can be done with extreme precision by reason of the construction. The stiffness of the spacer, or its resistance to compression, serves as a lock for the threads of the bolt I8 so that the latter cannot work loose and change the adjustment of the air gap. Also, by this arrangement, assembly is a simple matter and machining of the magnet I9 is reduced to drilling the hole for bolt I6.

Although anchored to the base plate I0 at II, the plate I2 is fulcrumed at an intermediate point on the yoke 2| having a. threaded stud 22 projecting through a longitudinal slot 23 in the base I0, as shown in Figs. 1, 2 and 5, The yoke 2| is adjustable along the plate lwithin the length of the slot 23 and is locked in any adjusted position by the nut 24 or stud 23. the nut 24 clamping the base flanges 25 around the slot 23 between it suits in concomitant -bodily vibration of the entire receiver. Since the mass ofthe magnet I3,

Y the weight 28 and the other vibrating parts, is

considerably greater than that of the plate l2 and the housing the vibration is the result of inertia reaction, so that the vibration is powerful and readily distinguishable and intelligible even "in severeconditions of deafness or magnitude of surroundingsounds.

It will thus be seen that a very simple but effective bonetelephone receiver, readily adaptable bending of the plate |2 takes place in response to vibration of the free end of the magnet I3 by the voice currents traversing coilv I4. Forexample, a shorter spring provides greater stiness which,'with about same mass, gives a higher pitch.

Thus the nearer the .fulcrum yoke 2| is posi? tioned to the anchor point the greater the stroke and the lower the pitch, and vice versa. 'I'he air gap 20 may be readily adjusted to accommodate an increased or decreased stroke simply by drawing upon bolt I6 for increased stroke, and vice versa for decreased stroke. In this way, the air gap adjustment afforded by the bolt I6 and spacer |'I combination cooperates with the pitch adjustment afforded by the shiftable fulcrum yoke 2|.

The adjustment of pitch is, also effected by shifting the center of mass of the relatively heavy vibratory magnet |9 and its appurtenant parts. Included among lthese vibratory parts is a weight 28 .having upwardly converging side arms 29 which cooperate with the upwardlyconverging sides of the magnet I 9 to hold the weight 28 thereon.

The weight is slidable along the magnet |9 and is locked in any adjusted position therealong by shown particularly in Figs. 1 and 2. Thus, by i changing'the position of the weight 28 along the magnet I9, the center of mass thereof is shifted, so that the frequency of its vibration is altered correspondingly, i. e., the nearer the weight 28 is positioned toward the free end of the magnet I9, the lower the frequency, and vice versa;

The air. gapZ adjustment aiforded by the bolt |6 and deectable spacery|1 also cooperates with the frequency adjustment just described to enable a wide rangeoffrequencies to be accommodated in one instrument.

The receiver includes a suitable cover 32 secured on the base Ill, by screws 33 or the like, andI is suitably supportedin -contact with the bone, such as on the mastold bone behind the to universal use, is provided by this invention,

and although a preferred embodiment of the in- .vention is illustrated and described herein, it is to be understood that the invention is not limited thereby, but is susceptible of change in form and detail Iwithin the scope of the appended claims.

I claim:

l. In a bonetelephoneireceiver, the combination of a base, a plate iixed at o ne end to and otherwise spaced from said base, an elongated lmagnet supported thereon at another end and forming an air gap therewith at its-fixed end, said magnet and plate forming a magnetic path across said air gap and including a voice coil, whereby the magnet and plate vibrate relatively to each other in response to the voice currents traversing said coil, a support on said base engageable with said plate intermediateits ends, and means for shifting said support to change the pitch of the receiver.

2. In a bone telephone receiver, the combinaticn 'of a plate, an elongated magnet supported thereon at one end and forming an air gap therewith at its other end, said magnet and plate forming a magnetic path across said airA gap and including a voice coil, whereby the magnet and plate vibrate relatively to each other in response to the voice currents traversing said coil, a sup-1 port for said plate intermediate its ends, means for shifting said support to change the pitch of the receiver, and means for adjusting said air gap 'to accommodate the change in pitch of the receiver. y v 3. In a bone telephone receiver, the combina.- tion of a plate, an'elongated magnet supported thereon at one end and forming an air gap therewith at its other end, said magnet and plate forming a magnetic path across said air gap and including a voice coil, whereby the magnet and plate wbrate relatively to each other 4in response to the voice currents traversing said coil, a housing for said plate and magnet, means fixedly connesting an end of said plate adjacent said voice coil to said housing with the plate otherwise j spaced from saidhousing, and a support movably mounted on said housing engageable with said ear, by means of a head-band pivoted on the base I0 as is partially shown at 34 in Fig. 3, or in an aviators helmet, or by other suitable supporting means. V

In operation, the receiver is adjusted to the desired pitch in the manner described with commensurate a'ir gap adjustment, and is placed with its base III in contact with the bone of the user,

such as on the mastoid bone behind the ear. The

voice currents, or currents representing other sounds within the audible frequency range, traversing coil I4 vary Vthe flux acrossthe air gap 20 and cause relative vibration of the Amagnet |9 about the fulcrum yoke2l. 'Ihe relatively,

stiif connection between the plate I2 and the vibrating magnet I9, causes a reaction which resaid magnet and plate which is imparted by the latter to the bone, a weight adjustable along said .magnet for adjusting the pitch of the receiverl a support forsaid platelshiftable.alongsaid plate to adjust the pitch ofthe receiver, and means for adjusting the air gap to accommodate the said pitch adjustments. T. WEIDENMAN, SR. 

